Multi-tiered computer networks are widely used to provide one or more users with a wide variety of information and computer resources. In multi-tiered computer networks, client computers (e.g., users) interact with server computers to is perform an application which is partitioned into one or more transactions. An application is a group of meaningful transactions, and a transaction is a unit of meaningful work as perceived by the user. A transaction is typically a collection of service requests, with the service request typically being a collection of service packets. A service packet is simply an item of information, or a message, communicated between computers. In the course of performing a transaction, the client computer may request one or more of the server computers to transfer service packets containing data to the client computer or provide service packets containing data to the server computer(s) to permit the server computer(s) to process the request. The server computers can in turn request the services of other server computers in connection with the data transfer request from the client computer.
Performance monitoring of the network is important to ascertain periods of significant transaction user delays and user productivity. Performance monitoring generally seeks to measure the response time for a transaction or application. The response time is the time required for the servers and network to perform the transaction or application. Statistical analysis can be performed on the response times to facilitate analysis of servers and network performance.
Two methods are commonly used to monitor network performance and provide response times. Intrusive/invasive monitoring techniques alter the software code on the client computer to include a marker command. The marker commands inform a listening device of transmission of the initial service request packet to initiate timing measurement and receipt of the final results or acknowledgement packet to cease timing measurement. Non-intrusive/non-invasive monitoring techniques, in contrast, typically do not alter the software code. Rather, a probe is inserted into a communication line between the client and server computers to monitor the delays between transmission of individual packets between the client and server computers to provide a rough estimate of response time.
Intrusive/invasive and non-intrusive/non-invasive techniques each have a number of drawbacks. In the case of intrusive/invasive techniques, though the transaction response time is provided, few multi-tiered applications are written with embedded marker commands in the code. Even if the applications were to have embedded marker commands, technical problems, can arise due to and consolidation of application-embedded response time statistics to a central location, especially for mobile user computers. In the case of non-intrusive/non-invasive techniques, it is only possible to determine the rate of information transmission between the computers for individual packets. Such techniques are typically unable to determine the response time for a transaction or application. Neither intrusive/invasive nor non-intrusive/non-invasive monitoring techniques are able to match, especially in multi-tiered networks, individual packets with the corresponding transaction to compute a response time for the transaction or related application. As noted above, each of the server computers performing an application can process a series of individual service requests pertaining to a variety of different user transactions. Existing monitoring techniques are unable to match the service packets in the various service requests to a specific transaction.
There is a need for an apparatus and method for measuring the response time for a transaction or an application, especially in multi-tiered computer networks. There is a related need for an apparatus and method for measuring the response time for a transaction or an application using nonintrusive/non-invasive techniques.
There is a need for an apparatus and method for measuring the response time for a transaction or an application that is able to match individual service packets with the corresponding transaction or application.